Belt grinding machine

ABSTRACT

A belt grinding or sanding machine of the type incorporating at least one endless grinding belt guided by at least two rollers and a clamping bar or pressure beam located diagonally at the inside of the grinding belt between such rollers and serving to press such grinding belt against the workpiece. According to important aspects of the invention, the aforementioned at least two rollers are arranged at the region of the respective ends of the clamping bar, with the respective axis of such rollers being inclined in opposite direction with respect to one another. Such imparts a predetermined curvature to the grinding belt. The clamping bar is arranged in the lengthwise direction of such predetermined curvature of the grinding belt.

United States Patent lnventor Guido Mung St. Gall -Winkeln, Switzerland Appl. No. 30,377 Filed Apr. 21, 1970 Patented Jan. 11, 1972 Assignee Ulrich Steinemann AG Maschinenfabrik St. Gall, Switzerland Priority Apr. 25, 1969 Switzerland 6336/69 BELT GRINDING MACHINE 7 Claims, 4 Drawing Figs.

0.8. CI 51/139, 51/140 Int. Cl B24b 21/08 Field oiSearch ..5l/137-139, 140, 141

References Cited UNITED STATES PATENTS 5/1900 Brinkman 51/139X Primary Examiner- Donald G. Kelly Attorney-Werner W. Kleeman ABSTRACT: A belt grinding or sanding machine of the type incorporating at least one endless grinding belt guided by at least two rollers and a clamping bar or pressure beam located diagonally at the inside of the grinding belt between such rollers and serving to press such grinding belt against the workpiece. According to important aspects of the invention, the aforementioned at least two rollers are arranged at the region of the respective ends of the clamping bar, with the respective axis of such rollers being inclined in opposite direction with respect to one another. Such imparts a predetermined curvature to the grinding belt. The clamping bar is arranged in the lengthwise direction of such predetermined curvature of the grinding belt.

PATENIEB JAM 1 m2 31 -33319 SHEET 1 OF 2 INVEMOR 6 1/00 Mfifl BY alu d M ATTORNEY sis-same PATENTEU JANI 1 me SHEET 2 BF 2 INVILQ'TOR Ga I b o M419 6 BYLWW M ATTORNEY BELT GRINDING MACHINE BACKGROUND OF THE INVENTION The present invention relates to a new and improved belt grinding or sanding machine embodying at least one endless grinding belt guided by at least two rollers, and further, incorporates a clamping bar or pressure beam located diagonally at the inside of the grinding belt, bearing against such grinding belt and pressing the latter against the workpiece.

I In contrast to contact grinding machines, in belt grinding or sanding machines the grinding belt is not pressed against the workpiece by a contact roller simultaneously functioning as a deflecting roller, rather the work surface of the grinding belt is disposed between both deflecting rollers. Belt grinding machines possess the advantage that a large number of abrasive grains simultaneously contact the workpiece with a small cutting depth, so that a good surface quality is achieved.

With contact grinding machines the contact path of the individual abrasive grainstravels in an arc-shaped configuration and leaves at the workpiece a relatively short, deep track. With differences in thickness of the grinding belt, for instance at the location of the seam, this defect of the band appears in the form of a line at the workpiece. Yet, such type equipment does, however, have the advantage that it is possible to immediately solve without difficulty the problems with respect to the presence of the grinding shavings or chips and the removal of heat. Furthermore, the workpiece can be easily introduced into the machine without necessitating prior lifting of the contact roller.

With the known belt grinding machines, the grinding belt bears along a longer path against the workpiece, so that the thus formed grinding dust cannot be immediately removed, rather is entrained by the band or belt. Consequently, the surface of the grinding belt is increasingly clogged in the direction of the belt, so that the grinding action is reduced in the same direction. Therefore, it has been proposed to equip the machine, in the feed direction of the workpiece, with two adjacently situated and oppositely revolving grinding belts. However, in so doing it cannot be prevented that the workpiece at its central region is only subjected to a smaller grinding or sanding action. Furthermore, due to the flat contact of the grinding belt the removal of heat is hindered and a new workpiece can only be introduced into the machine after previously raising the grinding belt. The raising of the belt requires an additional expenditure of time, and the subsequent new adjustment constitutes a possible source of error.

SUMMARY OF THE INVENTION Accordingly, it is a primary objective of the present invention to provide an improved belt grinding machine which effectively overcomes the aforementioned drawbacks of the prior art constructions.

Another, extremely important object of this invention relates to the provision of a new and improved belt grinding machine which combines both the advantages of a contact grinding machine as well as the advantages of a belt grinding machine, and thus, avoids the drawbacks of these known machines.

Yet a further significant object of the present invention relates to the provision of a new and improved belt grinding or sanding machine which is relatively simple in construction, economical to manufacture, easy to use, and not readily subject to breakdown.

Now, in order to implement these and still further objects of the invention, which will become more readily apparent as the description proceeds, the inventive belt grinding machine contemplates that the axes of at least two guide rollers arranged at the region of the ends of the clamping bar or pressure beam are inclined in an opposite direction from one another and the clamping bar is arranged in the lengthwise direction of the resulting curvature of the grinding belt.

Due to this inventive construction of the belt grinding machine, the working surface is curved or domed similar to the situation prevailing at a contact grinding machine, so that a new workpiece can be easily introduced into the machine and the grinding waste, chips, turnings, dust and the like, as well as the resulting grinding heat can be easily removed. However, the movement of the individual abrasive grains occurs diagonally and approximately in the lengthwise direction with regard to the curvature of the grinding belt, and not as in the case of the contact grinding machine perpendicular to the axis of curvature of the grinding belt.

Furthermore, for the stepwise processing or machining of a workpiece or also for simultaneously machining a workpiece at both sides with a band grinding machine, it is possible to utilize a number of such type guided grinding bands or belts. The belt or band grinding machine can also be constructed in such a way that adjacent each deflecting roller there is arranged a further guide roller, wherein, for instance, only the further guide roller is inclined opposite to a corresponding guide roller at the oppositely situated side of the machine or the clamping bar.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood and objects other than those set forth above will become apparent, when consideration is given to the following detailed description thereof. Such description makes reference to the annexed drawings wherein:

FIG. 1 schematically illustrates an embodiment of the invention regarding the arrangement of the grinding belt possessing the clamping bar in relation to the feed direction of a workpiece;

FIG. 2 is an enlarged sectional view taken along the line aa of the arrangement of FIG. 1;

FIG. 3 is a simplified schematic side view of a belt grinding machine incorporating an upper and a lower grinding belt or band; and

FIG. 4 is a simplified plan view of the belt grinding machine depicted in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in the exemplary embodiment of belt grinding or sanding machine depicted in FIG. I the workpiece 1 moves in the direction of the arrow 2, whereas the pulling run or strand 3a of the grinding belt or band 3 moves in the direction of the arrow 4. In order to preserve clarity in illustration, the return run or strand 3b of the grinding belt 3 which moves in the opposite direction is only partially shown. Furthermore, the axes of the deflecting rollers 5 and.6 are oppositely inclined with respect to the plane of the workpiece 1, so that the portion 30 of the grinding belt 3 which extends substantially parallel to the plane of the workpiece I, as best shown by referring to FIG. 2, defines a diagonally lengthwise extending curvature over the grinding belt 3 and this grinding belt only comes into contact with the workpiece along the apex of this curvature. Furthermore, the clamping bar or pressure beam 7 bearing against the inside of the grinding belt 3 is appropriately located in this longitudinal curved portion of such belt. It will be understood that it is easy to remove grinding dust and heat out of the spaces 8 and 9 beneath the grinding belt 3 due to the sides of the grinding belt being raised above the surface of the workpiece I, as shown in FIG. 2.

In the exemplary embodiment the grinding belt 3'is arranged in such a manner that its lengthwise curvature resulting from the inclination of the deflecting or guide rollers 5, 6 extends perpendicular to the feed direction of the workpiece 1. Of course, the grinding belt 3 can also enclose a different angle with the feed direction of the workpiece l.

The contact direction of the individual grinding or abrasive granules at the workpiece l is defined by the resultant of the velocity component of the grinding belt 3 and the workpiece l. The individual grinding or abrasive grains move in a linear path in engagement with the workpiece 1 under the pressure of the clamping bar 7.

Now, in the variant form of belt grinding machine depicted in FIGS. 3 and 4 such will be seen to be equipped with a respective upper and lower grinding unit. In order to preserve clarity in illustration, in FIG. 3 the grinding belts are not shown. Furthermore, the nonillustrated workpiece is introduced into this machine between the transport or conveying rollers and 11 and is fed from the right towards the left, to thereby initially be machined at its upper surface by the grinding unit 12 and thereafter at its lower surface or side by the grinding unit 13. Furthermore, at each side of the machine two guide rollers 14 and 15 are situated at the deflecting or turning locations of the grinding belt, of which one such roller possesses a larger diameter and serves as the deflecting roller 14. In this exemplary embodiment, the axis of the deflecting roller 14 encloses only a small angle B of for instance 2 30' with respect to the plane of the workpiece, whereas the smaller diameter guide roller 15 encloses an angle a of, instance, l7. Due to the different inclination of the adjacently situated guide rollers, there should be prevented a sliding off of the grinding belt from the deflecting rollers. Additionally, by virtue of the pronounced inclination of the guide rollers 15 the sides of the grinding belts are raised above the plane of the workpiece, so that the air sucked up through the suction hood l6 and 17 can entrain the grinding chips or shavings collecting beneath the associated grinding belt. Furthermore, the air which flows along beneath the grinding belt also ensures for the withdrawal of the grinding heat from the grinding location.

In this embodiment of the machine the clamping bars or pressure beams 18 and 19 extend parallel to the transport or conveying rollers 10 and 11. The transport rollers 11 are located above and below the clamping bars 18 and 19, respectively, at a spacing corresponding to the thickness of the workpiece. Furthermore, these transport rollers 11 possess a larger diameter than the remaining transport or conveying rollers 10, in order to absorb the grinding pressure and the contact pressure of the clamping bars 18 and 19. The direction of the grinding belts 20 and 21 is dependent upon the position of the clamping bars and the spacing of the guide rollers at both sides of the machine, and encloses with the lengthwise or longitudinal axis of the clamping bar, in other words, the lengthwise curvature of the grinding belt, an angle of approximately 7 in the present example.

At the machine housing 30 there is arranged a carrier 31 for the lower grinder unit arranged at the, left side of the equipment of FIG. 3, and a suitable similar carrier 32 is also provided for supporting the upper grinding unit arranged to the right of FIG. 3. Additionally, the carrier or support means 33actually there is one carrier element 34 thereof on each side of the bank of upper conveying rollers 10 and 11, and only one such carrier element 34 is visible in FIG. 3supports the upper bank of conveying rollers 10 and 11 as well as a table 35. This table 35 serves as a convenient temporary support for laying a new grinding belt thereon when the used one must be replaced and thus facilitates mounting of the new belt. Interposed between the carrier means 34 and the table 35 is a spacer 36 to ensure for the correct height or elevational spacing above the conveying rollers, the spacer 36 and table 35 being fixed by a supporting plate 37 to such carrier means.

Furthermore, at the traction or pulling side of each grinding belt the latter is equipped with a suitable drive motor 22, which, for example, is coupled with a deflecting roller via a V- shaped pulley belt. In the embodiment of FIG. 4, the drive motors are arranged upon the right side of the machine viewed in the feed direction of the workpiece, so that the grinding belt displaces the workpiece from the left towards the right. The drive motors, the guide rollers of the grinding belts, the clamping bars as well as the transport rollers, are secured or mounted at the frame 23 of the machine.

Apart from the easy introduction of the workpiece beneath the grinding belt or belts and the improved withdrawal of the grinding chips or tumin s and the heat from the rinding location, it 15 also possible, ue to the raised sides 0 the grinding belts away from the workpiece, to arrange in the spaces 8 and 9 between the grinding belts and the plane of transportation of the workpiece suitable guide members 24 and 25, by means of which the workpiece is secured in its position in the direct neighborhood of the grinding location.

While there is shown and described present preferred embodiments of the invention, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.

Accordingly, what is claimed is: I

l. A belt grinding machine for a workpiece, comprising at least one endless grinding belt, at least two rollers over which said grinding belt is trained, a clamping bar disposed at the inside of said endless grinding belt between said rollers, said clamping bar extending diagonally with respect to said endless grinding belt and pressing said endless grinding belt against the workpiece, said at least two rollers being disposed at the region of the respective end of said clamping bar and the axis of each roller being oppositely inclined with respect to one another, said endless grinding belt thus being curved along the direction of its lengthwise extent, said clamping bar being arranged in the lengthwise direction of such curvature of said endless grinding belt.

2. A belt grinding machine for a workpiece as defined in claim 1, wherein each of said rollers defines a deflecting roller for deflecting said endless grinding belt, and a guide roller arranged adjacent each deflecting roller.

3. A belt grinding machine for a workpiece as defined in claim 2, wherein the diameter of each of said guide rollers is smaller than the diameter of said deflecting rollers.

4. A belt grinding machine for a workpiece as defined in claim 2, wherein said guide rollers are inclined at a greater angle of inclination than said deflecting rollers.

5. A belt grinding machine for a workpiece as defined in claim 1, further including means defining a transport path for a workpiece, said one endless grinding belt being arranged above said transport path, and a further endless grinding belt arranged below said transport path, said one endless grinding belt and said further endless grinding belt machining the workpiece at both sides.

6. A belt grinding machine for a workpiece as defined in claim 1, wherein said clamping bar is arranged perpendicular to the feed direction of the workpiece.

7. A belt grinding machine for a workpiece as defined in claim 1, wherein said clamping bar and rollers cooperate with said endless grinding belt in such a manner that the sides of said grinding belt are raised, and guide means arranged in the spaces formed between said raised sides of said grinding belt and the plane of movement of the workpiece in order to secure the position of the workpiece at the direct neighborhood of the grinding location. 

1. A belt grinding machine for a workpiece, comprising at least one endless grinding belt, at least two rollers over which said grinding belt is trained, a clamping bar disposed at the inside of said endless grinding belt between said rollers, said clamping bar extending diagonally with respect to said endless grinding belt and pressing said endless grinding belt against the workpiece, said at least two rollers being disposed at the region of the respective end of said clamping bar and the axis of each roller being oppositely inclined with respect to one another, said endless grinding belt thus being curved along the direction of its lengthwise extent, said clamping bar being arranged in the lengthwise direction of such curvature of said endless grinding belt.
 2. A belt grinding machine for a workpiece as defined in claim 1, wherein each of said rollers defines a deflecting roller for deflecting said endless grinding belt, and a guide roller arranged adjacent each deflecting roller.
 3. A belt grinding machine for a workpiece as defined in claim 2, wherein the diameter of each of said guide rollers is smaller than the diameter of said deflecting rollers.
 4. A belt grinding machine for a workpiece as defined in claim 2, wherein said guide rollers are inclined at a greater angle of inclination than said deflecting rollers.
 5. A belt grinding machine for a workpiece as defined in claim 1, further including means defining a transport path for a workpiece, said one endless grinding belt being arranged above said transport path, and a further endless grinding belt arranged below said transport path, said one endless grinding belt and said further endless grinding belt machining the workpiece at both sides.
 6. A belt grinding machine for a workpiece as defined in claim 1, wherein said clamping bar is arranged perpendicular to the feed direction of the workpiece.
 7. A belt grinding machine for a workpiece as defined in claim 1, wherein said clamping bar and rollers cooperate with said endless grinding belt in such a manner that the sides of said grinding belt are raised, and guide means arranged in the spaces formed between said raised sides of said grinding belt and the plane of movement of the workpiece in order to secure the position of the workpiece at the direct neighborhood of the grinding location. 